Sulfonation of petroleum



ilnited States Patent 6 SULFONATION OF PETRGLEUM Samuel E. Jolly, Ridley Park, Pa., asignor to Sun Oil Company, Philadelphia, Pa., a corporation of New Jersey No Drawing. Filed Mar. as, 1958, Set. No. 723,658

5 Claims. 01. zen- 504 This invention relates to sulfonation of petroleum, and more particularly to sulfonation under conditions promoting the separation of oil-insoluble sulfonation products from the unsulfonated oil. v g

It is known in the art to sulfonate petroleum fractions such as gas oil or lubricating oil fractions by contact with a sulfonating agent such as anhydrous S0 fuming sulfuric acid, concentrated sulfuric acid, etc. It is also known to separate the oil insoluble sulfonic acids or green" sulfonic acids,- which are formed in thesulfonation, by permitting the green acids to settlefirom the unsulfonated oil. It is found, however, that not all of the green acids can be separated in this manner since a portion thereof remains suspended in the oil. It is also found that the suspended green acids cannot satisfactorily be filtered by ordinary filtration procedures, such as by means of a plate-and-frame filter press or rotary filter. It has been proposed in the prior art to improve the filtration by the addition of various known filter aids, but such operation is often undesirable, and it would be beneficial to improve the filtration characteristics of the green acids without resort to such filter aids.

According to the present invention the filtration properties of the green acids are substantially improved by performing the sulfonation in the presence of a small amount of an aldehyde. It has been found that such sulfonation results in modification of the properties of the green acids, permitting substantially all of the green acids to be readily filtered from the unsulfonated oil.

In one embodiment, the invention involves sulfonating a charge stock which is a rafiinate obtained in previous refining of petroleum by means of furfural. It is known in the art to sulfonate furfural raffinates, and the ordinary practice is to strip furfural from the rafi'inate prior to the sulfonation, so that the furfural content of the oil which is sulfonated is quite low, for example below 0.1 weight percent based on the rafiinate. In this embodiment of the invention, the ordinary practice is modified 'b'y substantially increasing the amount of furfural in the rai'finate which is sulfonated. The amounts of furfural in the raffinate as ordinarily produced are not sufiicient to provide the advantages according to the invention, whereas by increasing the amount of furfural, for example to a concentration of at least 0.2 weight percent, or in some cases at least 0.5 weight percent, the beneficial modification of the green acids is obtained. Preferably, the amount of furfural in the sulfonation charge is not substantially greater than 2 weight percent, since otherwise an adverse effect upon the sulfonation of the oil to produce desired oil-soluble or mahogany sulfonic acids may be obtained.

In this embodiment of the invention, it is preferred to conduct the stripping of furfural from the raflinate in the conventional manner, and then add furfural or another aldehyde to the resulting raflinate in order to obtain the necessary concentration of aldehyde in the sulfonation charge. However, it is within the scope of 2,94%,9a3 Patented June 14, 1%60 ice In the process according to the invention, the amount.

of aldehyde in the sulfonation charge, regardless of the identity of the aldehyde employed, is preferably within the approximate range from 0.2 to 2 weight percent based on the sulfonation charge. 7

The process according to the invention is believed to involve reaction of the aldehyde with green sulfonic acids, which are formed during the sulfonation, to form resinous products which have different properties from the green acids which are produced in conventional sulfonation processes. Any aldehyde which is reactive with sulfonic acids to produce resinous materials can be employed in the process according to the invention, such aldehydes being generally known as a class in the art. Aldehydes are here considered to include aldehyde polymers which are known to be capable of undergoing the characteristic copolymerization reactions of aldehydes. Examples of suitable aldehydes are furfural, formaldehyde, trioxymethylene, paraformaldehyde and acetaldehyde.

The sulfonation conditions which are employed in the process according to the invention are, aside from the presence of aldehyde, conventional sulfonation conditions, and any of the known sulfonation conditions can be employed. Usually the amount of sulfonating agent employed is sufficient to provide 10 to 25 pounds of- S0 per barrel of sulfonation charge. The temperature of the sulfonation is preferably within the approximate range from room temperature to 300 F. and more preferably 120 to 180 F. Any of the known sulfonating agents, such as anhydrous S0 fuming sulfuric acid and concentrated sulfuric acid, can be employed.

The charge stock for the sulfonation can be any of those which are known in the art, for example gas oil or lubricating oil fractions from paraffinic, naphthenic or mixed base crudes, etc. Usually the viscosity of the charge stock is Within the approximate range from Saybolt Universal seconds at 100 F. to 300 Saybolt Universal seconds at 210 F. Frequently the charge stock is a raffinate obtained in solvent refining of petroleum fractions employing any of the well known selective solvents for highly aromatic hydrocarbons, e.g. furfural, phenol, liquid sulfur dioxide, dichloroethyl ether, etc. In such solvent extraction, the ratfinate usually constitutes a fraction of the charge to the solvent refining, which fraction iswithin the approximate range from 60 to weight percent of that charge. Usually the rafiinate contains an amount of aromatic hydrocarbons within the approximate range from 10 to 25 weight percent of the total raifinate, aromatic hydrocarbons being those which contain one or more aromatic rings in the molecule.

Following the sulfonation, the liquid products are filtered, using for example a plate-and-frame press or rotary filter or other conventional filtration apparatus. It has been found that such conventional filtrations provide highly satisfactory results when the sulfonation is performed in the presence of aldehyde as disclosed previously, Whereas such filtration gives generally unsatisfactory results when the sulfonation is performed according to conventional technique. It is usually desirable to conduct the filtration in the presence of a diluent for the sulfonation products, for example petroleum naphtha, aviation alkylate, etc. The amount of diluent is usually Within the approximate range from 0.5 to 1 volume of diluent per volume of liquid sulfona tion product. The green acids which are produced in the sulfonation according to the invention generally consist of discrete granular particles which are readily file "have been removed is 1+ on the NPA scale. 'highly satisfactory color indicating essentially complete tered and readily removed from the filter hy conven-- ing a 2:1,ratio of fur-fural to an and a temperature of 'ta ins' about 12% In conventional steam stripping operatio ns,"the amount of iurfural is r'educedj'to 7 about 0.05%; 7 V According to the inventiomfu'rfural is then added back to theratfinate to obtain a' furfural content of about 1%. p The raflinate containing the-added 'fu'rfural is then 'fonic acids,-thereby to form a solution-oi oil-soluble 'sulfonat'ed employing a mixture of sulfur-trioxide vapor and air as sulfonating agent. About 18 pounds of S0 per barrel of'oil are employed, and the final temperature soluble sulfonic 'acids'which are produced in the sul-fonationare granular solid materials which are suspended in the oil as the latter is removed'from the sulfonation zone. About-OJ volume or aviation alkylate per volume of sulfonation product is added to the oil removed from the filter byconventional means and do notshow any. disadvantageoustendency to plug'up the filter cloths or otherwise interfere with the operation of the filter.

- The filtrate is then treated in conventional manner for frenioval otthe dissolved mahogany sulfonic acids. The removal involves n'eutralizationof the acids by means 7 of alkali and extraction of the resulting salts from the oil by means of a 35% aqueous solution of isopropanol. The color of the oil from which the mahoganyv acids This is a a 0.05% furfural, the sulfonation results in the production of oil-insoluble sulfonic acids which form a viscous homogeneous tar. About 6% of such tarry green acids based on sulfonation charge settle from thesulfonation products, while another portion of the green acids constitutmg about 1%'based on the sulfonation charge, do

seconds at 210 f".

not settle from the oil and remain suspended-therein. These suspended acids are diflicult to remove by conventional filtration processes. They have a disadvan tageous tendency to plug up the filter cloths and otherwise interfere with the filtration, disadvantages which are substantially eliminated jin operation according to the invention with added fui'fural present during the sulfonation. 7 1 a ;The green acids which-are produced in sulfonation according to the invention are useful forwarious purposes including for example the productionlof synthetic resins useful as exchange resins, 'et It may be desirable insomeinstances to 'further -react the green acids with an aldehyde such as formaldehyde or; furfural, etc. in order to provide such synthetic resins.

The inventionrclaimed is:

1.v In a process for sulfonating petroleum which comprises contacting a sulfonating agent with a petroleum' fraction'containing at least '10 weight percent of aromatic hydrocarbons including hydrocarbons-reactive with said agent to form oil-soluble sulfonic acids and hydrocarhons reac tiv e with said agent to form oil-insoluble sulsulionic acidsinfunsulfouated' components of said petroleuni fraction, said solution normally containing suspended insoluble'sulfonic acids in a'form difiicult tos'ep' arateby settling and' filtration; the improvementfwhich comprises performing said' contacting" inthe presence of 0.2 to- 2.0 weight percent, based on said fraction, of an aldehydefselected frornfthegroup consisting" of furfural,

'formaldehyde, formaldehyde polymers, and acetaldehyde,

3.: Process according to claim' 1 wherein said petroleum is a distillatehaving;Saybolt Universal viscosity'within the approximate range from 75 seconds at 100 F. to 300 4. Process according to claim? wherein said distillate has previouslybeen'refined with furfural, the raflinate from the refining has been stripped to remove iurfural therefrom and'furfural has been added to the resulting raflinate to provide a concentration within the approximate range from 0.2-to 2%. 7

'5. Process according to claim l wherein' oil-insoluble sulfonic acids are filtered from the sulfonation products to obtain substantially complete removal of the oilinsoluble acids as a granular filter cake readily removable from the filter.

0 References Cited in'the file of this patent v UNITED; STATES PATENTS 2,330,163v Waldoet a1. Sept. 21, 1943 

1. IN A PROCESS FOR SULFONATING PETROLEUM WHICH COMPRISES CONTACTING A SULFONATING AGENT WITH A PETROLEUM FRACTION CONTAINING AT LEAST 10 WEIGHT PERCENT OF AROMATIC HYDROCARBONS INCLUDING HYDROCARBONS REACTIVE WITH SAID AGENT TO FORM OIL-SOLUBLE SULFONIC ACIDS AND HYROCARBONS REACTIVE WITH SAID AGENT TO FORM OIL-INSOLUBLE SULFONIC ACIDS, THEREBY TO FORM A SOLUTION OF OIL-SOLUBLE SULFONIC ACIDS IN UNSULFONATED COMPONENTS OF SAID PETROLEUM FRACTION, SAID SOLUTION NORMALLY CONTAINING SUSPENDED INSOLUBLE SULFONIC ACIDS IN A FORM DIFFICULT TO SEPARATE BY SETTLING AND FILTRATION, THE IMPROVEMENT WHICH COMPRISES PERFORMING SAID CONTACTING IN THE PRESENCE OF 0.2 TO 2.0 WEIGHT PERCENT, BASED ON SAID FRACTION, OF AN ALDEHYDE SELECTED FROM THE GROUP CONSISTING OF FURFURAL, FORMALDEHYDE, FORMALDEHYDE POLYMERS, AND ACETALDEHYDE, THEREBY TO REACT SAID ALDEHYDE WITH OIL-INSOLUBLE SULFONIC ACIDS TO FORM A PRODUCT HAVING SUPERIOR FILTRATION PROPERTIES TO THOSE OF THE OIL-INSOLUBLE SULFORNIC ACIDS. 